This invention relates generally to rehabilitation and exercise equipment, and more particularly, to a new and improved direct drive rehabilitation and fitness apparatus and method of construction which converts rotational to reciprocating motion for exercise therapy.
In the field of rehabilitation and exercise equipment, various types of machines are known, many of which employ a pulley-belt system connected to a weight stack or other resistance. The machine may be designed for use while the operator is in a seated or standing position. Other rehabilitation systems have included pulley-cable or chain-sprocket designs for connecting the weight stack to a main frame within the actuating mechanism. More advanced machine designs have included hydraulic, pneumatic and electrical resistance schemes.
An important consideration in the rehabilitation of injured joints and limbs is the movement path of the limb during therapeutic exercise. By definition, an eccentric movement of the arm is the extension of the arm along the axes of the elbow away from the shoulder resulting in the extension or stretching of the biceps muscle. Further, a concentric movement incorporates the contraction of the arm at the elbow to a collapsed position resulting in a contraction or flexing of the biceps muscle. These two movements are extremely important in the rehabilitation of the shoulder joint and are commonly prescribed for patients in physical therapy.
An example of a rehabilitation and exercise device known in the past included a drive apparatus mounted on a support structure. The support structure included a three dimensional broad base for providing stability to a vertical member which was mounted and diagnonally supported at the center of the base. The vertical member was comprised of a rectangular structure having a plurality of penetrations therethrough for receiving an adjustment pin.
The drive apparatus included a main frame for providing structural support which was also rectangular in shape and which was fashioned for fitting over the vertical member of the lattice shaped bottom support structure. Connected to the main frame in an orthogonal manner was a cross member which was employed for supporting the drive apparatus.
The drive apparatus was comprised of a rotary mechanism having a center axis. Connected to the center axis was an actuator bar which included a forearm cuff and a wrist cuff with corresponding securing straps for aligning a body limb with the axis of rotation of the drive apparatus. The apparatus permitted the limb of the operator to be aligned with the axis of rotation during the operation of the rotary mechanism. Also included was a pull pin which acted as a range limiter employed for adjusting the range of motion of the drive apparatus.
Connected to a forward part of the drive apparatus was a webbed belt which extended along a diagonal support member connected between the main frame and the cross member. At the interface between the diagonal support and the main frame, a first pulley was mounted for receiving and circuiting the webbed belt to and over a second pulley mounted at the top of the main frame. The belt was circuited over the second pulley and extended downward for connecting to an attachment piece for securing the belt to a weight stack support and guide.
The weight stack support and guide was employed for securing a stack of weights on the rehabilitation exercise device. The guide included a shaft passing through the weight stack and connecting to the attachment piece. Further, guidance was provided by passing the guide shaft through a plurality of alignment blocks for securing the guide shaft and the weight stack. It should be noted that although a webbed belt was employed in the instant rehabilitation device, a chain or cable could be employed utilizing the existing pulley or a toothed sprocket for mating with the chain.
Located along the main frame was a frame adjustment pin utilized for adjusting the height of the drive apparatus along the vertical member of the support structure. This adjustment permitted the machine to accomodate persons of different height so that the limb could be aligned with the axis of rotation of the drive apparatus. Also included was a cornerlock which was employed for stabilizing the rehabilitation device and for preventing the top portion of the drive apparatus from moving on or about the bottom support structure.
Further, a pressurized gas or hydraulic cylinder was located within the main frame and was employed when the top portion was released or disassembled from the bottom support structure. During such release or disassembly, the cornerlock was loosened and the adjustment pin was removed from one of the plurality of penetrations in the vertical member of the support structure. Although the attachment pin was employed for adjusting the height of the device, the cornerlock was utilized only for stabilizing the device during adjustment or for the total disassembly of the device.
A major problem associated with rehabilitation devices known in the past is that an operator can not use the same machine to perform both eccentric and concentric movement patterns. Thus, the devices in the past have not provided the convenience and capability of permitting an extension movement of the arm followed by a contraction movement of the arm, each along the axis of the elbow on the same machine. Further problems include the high maintenance factor associated with pulleys and chain or belt driven exercise devices. The frictional wear factor causes the structure elements to wear rapidly. Environmental conditions, particularly humidity will result in the belts stretching or contracting, each of which produce mechanical play in the operating mechanism.
Noise is an additional factor with this type of mechanical driven apparatus. A suitable engineering solution to minimize noise either results in increased design costs or increased maintenance costs. Friction also results in reduced efficiency and quality of the operation of the machine. A personnel hazard is also present when belts, chains, cables and pulleys are employed. Therefore, safety guards are required in these devices which also increases manufacturing costs.
Several attempts to solve these problems have resulted in evolution of rehabilitation devices. Initially, cable-pulley systems were common, however, cables were eventually replaced by chain-sprocket mechanisms which did not stretch. Eventually, the chain-sprocket mechanism was replaced by the webbed belt which generally improved the efficiency of the device. It is well known that rubber webbed belts generally last longer since cables and chains tend to wear because of friction produced by the mechanical engagement. In particular, the chain tended to wear because the pitch diameter of the chain resulted in wear to the sprockets. Further, failure to lubricate the sprocket resulted in additional wear. In addition, the required safety guards were a factor in eliminating chain driven devices. The webbed belt may be comprised of a fiber glass material in combination with a nylon webbing, the combination being a substantial improvement. However, the cost factor has been high since such a combination of materials is manufactured by and only available through limited sources.
Additional attempts to solve the aforementioned problems included hydraulic and pneumatic systems which provided a predetermined calibrated resistance to the movement of the drive apparatus by the operator. Another example included an electronic resistance element. This application included an electrical motor that provided a resistance when a mechanical load was applied to the motor shaft. The major problem associated with this application was inaccuracy due to the inability to calibrate the motor resistance properly. Although the electronic resistance device appeared to have potential, as with several rehabilitation devices of the past, it was cost prohibited.
Hence, those concerned with the development and use of rehabilitation and fitness equipment in the medical and physical therapy fields have long recognized the need for an improved rehabilitation apparatus which permits operation through opposing patterns of movement of opposing muscle groups on the same machine and which has a direct drive design that can be retrofitted to existing rehabilitation devices. Further, the apparatus can be manufactured and marketed at a substantial savings over other similar machines of the past and will eliminate cables, chains, belts, pulleys and safety guards associated therewith. Further, mechanical play in the mechanism is virtually eliminated minimizing frictional wear of components and reducing personnel safety hazards. The present invention fulfills all of these needs.